A log file or simply log is a file that records events taking place in the execution of a system in order to provide an audit trail that can be used to understand the activity of the system and to diagnose problems. The act of keeping a log file is called logging.
Logs are essential to understand the activities of complex systems like wireless communication devices, particularly in the case of applications with little user interaction. It may be useful to combine log file entries from multiple sources like network, radio, events and applications. Statistical analysis of these files may yield correlations between seemingly unrelated events which in turn help device manufacturers and network operators improve their product quality and performance.